The dimerization of acetylene can be accomplished with a Nieuwland catalytic system. A Nieuwland catalyst is composed of copper chloride (CuCl) and potassium chloride (KCl) or ammonium chloride (NH4Cl) in an aqueous media. The process generates monovinylacetylene, with a small amount of divinylacetylene, and without the formation of benzene, or the formation of a linear acetylene trimer, or oligomers.
The use of CuCl2 for the dimerization of acetylene is shown in U.S. Pat. No. 3,957,899. One of the problems with the use of CuCl2 is the low solubility of Cu(I) in a homogeneous solution. The Nieuwland catalyst addresses this by the addition of potassium chloride or ammonium chloride to increase the Cu(I) in solution.
Currently there is no heterogeneous catalyst for the dimerization of acetylene. A good heterogeneous catalyst can improve the conversion of acetylene to higher value products such as vinylacetylene and the process for product separation.